1. Field of the Invention
The present invention relates generally to micro-electromechanical (MEMS) devices and, in particular, to arrayed magnetically actuated MEMS devices such as arrayed mirrors used in optical switches.
2. Description of Related Art
Optical switches are used for routing optical (i.e., light) signals in fiber optic networks. The switches are used to selectively transmit light signals from a set of input fibers to a set of output fibers. The switches typically include an array of movable mirrors or reflectors that can be selectively actuated to deflect light signals to particular output fibers.
The mirror arrays are typically fabricated using MEMS manufacturing processes, which involve using silicon processing and related techniques common to the semiconductor industry to form micro-electromechanical devices.
The movable mirrors can be actuated or controlled in a variety of ways including through electromagnetic actuation, electrostatic actuation, piezoelectric actuation, stepper motors, thermal bimorph and comb-drive actuation.
One problem with prior art optical switches is that high voltages are needed for mirror actuation, which raises the cost of operating the switches.
Another problem with prior art switches is that they require continuous power to retain functionality. Mirrors in the array that have been actuated from a rest position are not stable, i.e., they do not remain in an actuated state if power is removed from the switch. Accordingly, power must be continuously applied to maintain mirror positioning, even if no further switching occurs.